Our aim is to study the functions of the primate superior colliculus by employing three converging approaches: ablation, stimulation and single-cell recordings. 1. Ablation studies will determine effects of superior colliculus removal on specific behavioral tasks involving spatial orientation and sensori-motor control. 2. Stimulation studies will investigate behavioral responses of alert animals in which the colliculus, frontal eye fields and visual cortex are stimulated. Part of this work will investigate the effects of stimulation of any two of these structures when the third is ablated. 3. Recording studies will analyze the characteristics of single units in the primate colliculus; both receptive field characteristics and eye- movement related activity will be studied in alert animals in which one eye has been immobilized.